A semiconductor module includes a base plate having an inner region adjacent an edge region, a substrate attached to the inner region of the base plate and a heat sink on which the base plate is mounted so that the base plate is interposed between the substrate and the heat sink and at least part of the inner region of the base plate contacts the heat sink. The module further includes a stress relief mechanism configured to permit the base plate to bend away from the heat sink in the edge region responsive to a thermal load so that at least part of the inner region of the base plate remains in contact with the heat sink.